As the communication services continuously develop, a communication network requires larger transmission bandwidth and transmission capacity. Therefore, a Dense Wavelength-Division Multiplexing (DWDM) system is widely used. In order to prevent the multi-wavelength optical crosstalk, the output light wave of each optical-module laser must work at a particular wavelength. The wavelength of a laser varies with the temperature, and there is a system in a common optical module for locking and controlling the wavelength, so as to control the wavelength in a desired range. Scrambling technology is applied in the locking and controlling process of the wavelength, and a conventional scrambling manner is to perform scrambling on each laser respectively. In the multi-wavelength DWDM application, if the conventional manner of scrambling each laser is used, the area of a Printed Circuit Board (PCB) and the complexity of a control circuit are definitely increased significantly.
In the current technology for controlling and locking multiple wavelengths, multi-channel “scrambling” is performed to discriminate currently controlled and locked wavelengths, and in an each wave scrambling retrieval manner, an Analog-Digital Converter (ADC) samples a digital signal, and a micro-processor performs Fast Fourier Transformation (FFT) on the digital signal, so as to retrieve different scrambling frequencies of different waves, as shown in FIG. 1. However, each wave must be added with a unique scrambling frequency, the responsivity of a wavelength locker is small, and a photoelectricity detector (PD) signal output from the wavelength locker directly enters the ADC so as to be sampled, which imposes high requirements on the accuracy of the ADC. As the wave number increases, required hardware and software resources are increased dramatically, and critical resources such as Digital/Analog (DA) lane number and micro-processing capability are also challenged.